A known sampled grating (SG: Sampled Grating) has a configuration wherein a plurality of segments each composed of a diffraction grating portion with a diffraction grating and a space portion are coupled. There is the known technology of attaching a phase adjusting mechanism to the sampled grating and controlling it, thereby implementing selection of an arbitrary wavelength (e.g., cf. Patent Literature 1).
Patent Literature 1: Japanese Patent Application Laid-Open No. 2011-249618